6-3.rb

class Bicycle
  attr_reader :size, :style, :tape_color, :front_shock, :rear_shock

  def initialize(args)
    @style       = args[:style]
    @size        = args[:size]
    @tape_color  = args[:tape_color]
    @front_shock = args[:front_shock]
    @rear_shock  = args[:rear_shock]
  end

  # styleの確認は危険な道へ進む一歩
  def spares
    if style == :road
      {
        chain: '10-speed',
        tire_size: '23', # milimeters
        tape_color: tape_color,
      }
    else
      {
        chain: '10-speed',
        tire_size: '23', # inches
        tape_color: tape_color,
      }
    end
  end
end


class MountainBike < Bicycle
  attr_reader :front_shock, :rear_shock

  def initialize(args)
    @front_shock = args[:front_shock]
    @rear_shock  = args[:rear_shock]
    super(args)
  end

  def spares
    super.merge(rear_shock: rear_shock)
  end
end

mountain_bike = MountainBike.new(size: 'S', front_shock: 'Manitou', rear_shock: 'Fox')
p mountain_bike.size
p mountain_bike.spares